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  1. #21
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    My guess is the RS232 IC is fried on the inputs. I've successfully repaired this fault on my own machine by replacing this IC. Usually a single chip transceiver directly attached to the RX and TX lines near the serial connector.

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    Quote Originally Posted by duwerk View Post
    For what it's worth, I'm using a laptop with the following setup to drip feed and send/receive without issue:

    Machine/Control: Compumill 4000 with Dynapath Delta 20
    USB to serial adapter: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
    Null modem crossover adapter: https://www.amazon.com/Monoprice-DB2.../dp/B001VL8RK2
    NC link DNC software(Free): CAD/CAM CNC | Downloads Page | OneCNC CAD/CAM Software

    It might be related to the crossover adapter, I want to say I was able to receive originally as well but couldn't send/dripfeed until I had the pin-out corrected with the adapter. I don't have the specific null modem adapter I listed above, I got one from a buddy, but it just crosses your send/receive pins so any one will work.

    Good luck.
    I keep hearing about these null modem adapters. Thing is, I never had one before. The one that got fried by the lightning was just a straight-through pin-out. Why would I need the cross-over pin-out now?

    Thanks again for all your input guys. Much appreciated.

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    Have you performed a loopback test (mentioned by corednc in post #5) with your current setup? If the loopback test works you can know you have good communication out and back into the computer through your wiring and adapter. Here is a brief overview of how to perform the test: Loopback Test

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    Depends how your new adapter is wired. If your new adapter has a field wireable end you can switch pins there and try it again. Your old adapter may have been wired "correctly" for you from the beginning. The loopback test probably makes more sense to do first however.

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    Quote Originally Posted by BugRobotics View Post
    Have you performed a loopback test (mentioned by corednc in post #5) with your current setup? If the loopback test works you can know you have good communication out and back into the computer through your wiring and adapter. Here is a brief overview of how to perform the test: Loopback Test
    I have not performed the loopback test yet. I have been trying to avoid it. Once again, I'm a CNC programmer, not a machine tech. I guess I will have to learn how to do it though, so I can rule out anything on the PC side. Thanks for the link. Maybe it's not that hard...

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    Yea, not hard at all. Disconnect the serial connector from the machine and jumper RX and TX (usually pin #2 and #3 on a DB9 or DB25 connector). Then use Putty to start a serial connection

    Setting up a serial connection:
    putty-setup.jpg

    Starting a serial connection:
    putty-start.jpg

    After starting you will see a black window show up. This is where you input any letter to test the connection. If all is good with your setup you will see the same character you type show up in the window.

    For example if you typed "a" into the window, you would see "aa" because the "a" you typed went down the TX line and returned on the RX line. Hope this helps.

  7. #27
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    Quote Originally Posted by BugRobotics View Post
    Yea, not hard at all. Disconnect the serial connector from the machine and jumper RX and TX (usually pin #2 and #3 on a DB9 or DB25 connector). Then use Putty to start a serial connection

    Setting up a serial connection:
    putty-setup.jpg

    Starting a serial connection:
    putty-start.jpg

    After starting you will see a black window show up. This is where you input any letter to test the connection. If all is good with your setup you will see the same character you type show up in the window.

    For example if you typed "a" into the window, you would see "aa" because the "a" you typed went down the TX line and returned on the RX line. Hope this helps.
    Thanks for the tuteral...seems pretty easy. I did order a null modem adapter just to see if it works. I will have it tomorrow. And I will do the loopback test. We'll get this figured out one way or another. Stay tuned!

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    Purely FYI and not meant to discourage you from trying,

    I have in the past had devices pass a loopback test and still fail to function. I assume marginal voltage/power output, and longer cables was the reason, but don't know for sure. I have also seen the same stated as possible reasons why usb-serial converters are less reliable than hardware ports, but again no first hand evidence of this.

    One such device was an old anilam control I used to have. Troubleshooting guide dictated a simple jumpered db25 plug to perform loopback, and it passed everytime. But plug a cable in and it was always stone dead at the other end. I eventually got it to transmit a few lines of code over a ~12" long cable. Replaced the line drivers but it didn't help. Never did get that old POS to communicate with the computer in a useful way.

    Accordingly I am somewhat wary of relying too heavily on the loopback test as absolute proof of function...

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  11. #29
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    Quote Originally Posted by gregormarwick View Post
    Accordingly I am somewhat wary of relying too heavily on the loopback test as absolute proof of function...
    Great point and totally agree that it's not the end all be all of serial tests. Like you mentioned voltage levels can be a big deal as well as total capacitance of the cable run but that's getting into the weeds for now. A loopback test just lets you know your wiring is correct (as long as you jumper the right pins!) and that your USB to serial device is at least functional enough to send and receive data.

    If the loopback passes, I'd do the following:
    - Visually inspect the Haas serial input PCB connected to the DB25 connector. They have some resistors on the inputs you could check for continuity to ensure they weren't blown.
    - Double check the wiring at the connector to ensure the pinout is correct for the machine
    - Check various points along the path of the serial data going to the processor that is using the information (scope required)
    - Looking at the IC that accepts the TX and RX lines. After determining the IC you can check whether there is any outgoing data from the chip with a scope(after looking up the datasheet and determining pinout).

    If the lightening surge took out the computer, the serial adapter and a few boards on different machines it's more than likely the input side of those ICs went as well.


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